2 stage flushing for atomicity.
2 stage flushing for atomicity. ruby OK
Merge branch 'topic/atomic_flush' of github.com:akiradeveloper/dm-lc into topic/atomic_flush
bugfix. bug still remained but the issue is related to migration. not this branch alone
change migration principle. io_lock changed to mutex_lock for performance
dd runs. init_completion at startup and change schedule to schedule_timeout_interruptible. with schedule used spin cpu forever and accept nothing.
bugfix. crash recovery is still bugged.
bugfix. resume after dd test OK. dd -> resume -> dd -> ruby test OK.
refactored and add some skeltal code. still bug remained